A recent measurement of the universe’s expansion rate by the Hubble telescope has astronomers considering potential evidence that something strange may be happening in the cosmos.
Using NASA’s Hubble Space Telescope, scientists recently made the most precise measurement of the expansion rate of the universe to date.
The results of the Hubble measurement baffled researchers as it confirms a possible discrepancy in past measurements of the universe’s rate of expansion.
The results reportedly show that the universe is expanding way faster now than from just after the Big Bang. However, the increase in speed should not be a surprise as it was already a theory that scientists previously suspected.
The new measurement reportedly reduces the odds that this theory is a coincidence and that astronomers must find new ways to explain the phenomenon.
“The community is really grappling with understanding the meaning of this discrepancy,” Adam Riess, lead researcher of the study and a Nobel Laureate of the Space Telescope Science Institute and John Hopkins University, was quoted as saying.
The Hubble Measurement of the Expansion of the Universe
For the past six years, Riess and his colleague, Stefano Casertano, have been using the Hubble telescope to improve measurements of the distances between galaxies. They do this by measuring the distance between stars that serve as markers.
These measurements play significant roles in calculating the speed at which the universe expands with the passing of time.
The value of this Hubble measurement is known as the Hubble constant. Technically, constants must always have a single, fixed value.
However, the new calculation suggests a different value from the one that was made several decades ago. Based on Riess and his team’s computations, the stars they analyzed have distances that are ten times farther away into space than previous Hubble measurements.
Initial findings claimed that the universe is expanding at around 70 km per second per megaparsec. However, one result from the European Space Agency‘s Planck satellite shows that the expansion rate of the universe is closer to 67.8 km/s/Mpc.
While the difference is not that big, it’s enough to make astronomers pause in their tracks. The discrepancy was further reinforced by the Hubble measurement made by Reiss and his team.
The Plank’s result reportedly predicts that every galaxy within 3.3 million lightyears away from us is moving 67 kilometers per second faster.
However, Reiss’s team measured a value of 73 kilometers per second per megaparsec. This is an indication that these galaxies are moving at a faster rate than initially observed.
The new Hubble data is said to be so precise that astronomers can’t dismiss the measurement gap as mere errors.
“Both results have been tested multiple ways, so barring a series of unrelated mistakes, it is increasingly likely that this is not a bug but a feature of the universe.”
Discrepancy in the Universe’s Expansion Rate
There have been a few speculations about why the disparity in the universe’s expansion rate occurs. According to Reiss, one possible explanation is related to the fact that around 95 percent of the cosmos is shrouded in darkness.
It is said that dark energy, which is thought to accelerate the cosmos, has been moving the galaxies farther away from each other with growing strength. This means that the universe’s rate of acceleration is changing and not constant.
Another theory suggests that there may be a subatomic particle within the universe that travels close to the speed of light. These quick particles are commonly referred to as dark radiation and include particles such as neutrinos.
According to researchers, any of these speculations could change our understanding of the universe and may result in an incorrect value for the Hubble constant.
At this point, Reiss and his team have no concrete explanation for this issue. The team is still reportedly working on fine-tuning the expansion rate of the universe.
“Ordinarily, if every six months you try to measure the change in position of one star relative to another at these distances, you are limited by your ability to figure out exactly where the star is,” Casertano explained.
“This method allows for repeated opportunities to measure the extremely tiny displacements due to parallax,” Riess added. “You’re measuring the separation between two stars, not just in one place on the camera, but over and over thousands of times, reducing the errors in measurement.”